A vinyl chloride resin is either a homopolymer of vinyl chloride or a copolymer including 50% or more of vinyl chloride. The vinyl chloride resin is widely used as a material of various products including wires, electromechanical products, toys, films, sheets, artificial leather, tarpauline, tapes, food packing materials and medical supplies using foaming, extrusion, injection, calendering and the like.
However, the vinyl chloride resin has a processing temperature closer to a pyrolysis temperature, and therefore, has disadvantages of having a narrow formable temperature range, having high melting viscosity and having low fluidity. In addition, the vinyl chloride resin tends to adhere to a metal surface of processing instruments during high temperature processing, which frequently produces carbides, and as a result, various problems relating to processing such as quality decline of final formed articles occur. In view of the above, a processing aid and a lubricant are used for enhancing processing characteristics of the vinyl chloride resin.
A processing aid and a lubricant are additives improving melting delay characteristics of the vinyl chloride resin itself and thereby helping the vinyl chloride resin sufficiently exhibit various mechanical and chemical properties, and have been mandatorily used in processing of the vinyl chloride resin.
Specifically, Korean Patent Application Laid-Open Publication No. 2006-127730 proposed a method of reducing adhesion with metals by adding a multilayer-structured polymer lubricant including high-priced silicone-based latex, however, the method caused a new problem of poor processing due to the silicon.
In addition, Korean Patent Application Laid-Open Publication No. 2004-0047510 disclosed a use of a core-shell-structured acrylic processing aid, however, the use was not able to sufficiently reduce adhesion with metals as well, and was not able to resolve a problem of quality decline of final formed articles.
Particularly, a surface defect problem such as air marks, flow marks and fish eyes having various shapes appearing on the surface seriously occurred as well as the above-mentioned problems during calender forming for sheet processing of the vinyl chloride resin.
A method of adding a processing aid and a lubricant in large quantities has been proposed in view of the above, however, a new problem of transparency decrease has been caused.
Accordingly, means to reduce adhesion with metals and resolve a surface defect problem while maintaining transparency has been required, and such demands are very urgent considering the amount of the vinyl chloride resin used throughout the industry.